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With less than 10% of the RMGB region in farms, and only about one half of this in cropland, cultivated agriculture is not a primary land-use or economic activity by comparison with the major agricultural areas of the country. The two most intensively cultivated areas are southern Idaho and northern Utah, and eastern Oregon. Small grains, primarily wheat and barley, and potatoes are major crops in these localized areas. Hay crops, particularly alfalfa, occupy the most cultivated acreage in the total RMGB portions of 7 of the 8 states. Hay drops to second in Idaho where potatoes are first. Because hay and potatoes are irrigated crops, it is obvious that any climate-change effects on water resources would affect agriculture in the region. Most of the hay is sold as a cash crop, or is used by farmers as winter-feed for beef cattle and dairy cows.
In addition to the cropland agriculture, beef-cattle rearing is a widespread practice and most of the RMGB region is grazed by beef cattle. Although the beef cattle are owned by private ranchers most grazing occurs on public lands because the ranch properties are limited in size. For this privilege, the ranchers pay grazing fees to use the extensive federal lands (e.g., national forests maintained by the USDA Forest Service and Bureau of Land Management lands maintained by Dept. of the Interior) and state lands. In winter, these cattle are brought back to the home ranches to be fed hay produced on the property in summer, or purchased on the open market. The value of cattle and calf sales exceeds the value of any single cultivated crop in 5 of the 8 states. Even with so much activity, the realities of the semi-arid climate lead to sales being only about a third of total agricultural revenues, which are, themselves, a minor contributor to the states' economies.
Agriculture is clearly one of the sectors most likely to be affected by climate change because higher carbon dioxide (CO2) levels generally enhance plant growth (if important nutrients and water are not in short supply) and make plants more efficient water users. Computer model simulations of crop production under conditions of warmer temperatures, increased precipitation, and fertilization by elevated CO2 levels project increased yields of wheat, barley, and potatoes. The two grains (wheat and barley) are dryland crops and are not irrigated, and so would especially benefit from increased precipitation. Potatoes are irrigated, and the simulations were run on the assumption that the availability of water for irrigation would not change.
The simulations did not project as large an increase in hay yields, which are also irrigated. However, in these analyses the models assumed no change in the number of cuttings (crops) per year, currently two. It is quite likely that increased temperatures will lengthen the growing season and make possible three, or even, four hay crops per year. Total hay production would, therefore, be likely to increase.
Although the most important factors point toward a likely increase in agricultural productivity, uncertainties remain about some potential negative influences. For example, warmer winters might reduce cold-season pest die-offs, which could then increase the need for costly pesticides that in some cases can lead to environmental concerns. Increased temperatures could also encourage the increased growth of heat-tolerant weed species, creating a need for increased herbicide application. Hotter and more humid summers could also encourage molds and diseases that harm the region's tomato, potato, and sugar beet crops. However, some problems may also be alleviated, for example reduced snow cover in warmer winters could reduce snow mold that can harm wheat.
This analysis has been based on a projection of increased temperatures and precipitation. If climate change were to reduce precipitation, agriculture in the region would be more stressed, and competition for water resources would increase.
With its arid to semi-arid climate, increases in temperature and precipitation would almost certainly be beneficial to ranching and livestock grazing. For example, more abundant forage (plants used for animal food) production and longer grazing seasons would be beneficial influences. Increased hay yields would tend to reduce hay prices in the absence of other changes, and increased precipitation would reduce the need for irrigation and irrigation related costs.
Again there could be some opposing forces. Warmer temperatures could create problems of heat stress and pests for the livestock. Ranchers might need to switch to raising cattle strains that are more resistant to hot summer temperatures. Warmer temperatures are also known to reduce milk production in dairy cows.
The present rangeland is made up of plant species that are best adapted to current climatic and land-use patterns in the region. Climatic changes would almost certainly benefit some species and be detrimental to others. Those benefits and detriments could result in changing the species that are dominant in the ecosystem, which would be likely to open plant communities to invasion of non-native weeds. Were this to result, the quality of the range forage could decline, creating a need for costly weed controls.
The Intermountain West developed originally as a sparse-population, rural culture, emphasizing farming and ranching. Ranching, in particular, has been a way of life historically for many in the area, leaving an indelible mark in most people's image of this region. As a result, except around cities, the region remains largely undeveloped, with many areas being an open, semi-wild land that resembles its pre-Columbian condition. However, farming and ranching have experienced increasing economic problems in recent decades as competition for irrigation water and operating costs have risen, and commodity prices have dropped. Landowners have struggled with the dilemma of selling their land, often to real estate developers. As this occurs, the result is likely to be a fundamental change in the character of the region, and loss of a traditional American lifestyle and environment.
There is a growing realization in the West -- including among environmentalists who traditionally have been critical of livestock use on the range -- that ranching and farming are a bulwark against loss of open space, pell mell suburban sprawl, and leap-frog real estate development that can intrude on the rural, wilderness character of the region. If precipitation increases, enhancing agricultural and forage production, and reducing water competition, it could increase the economic viability of western agriculture and ranching. The result could be to preserve the western lifestyle, and stem the change in western landscapes.
If precipitation does not increase, or actually declines, the social impacts of changes in farming and ranching could reverberate throughout the RMGB. It would become much more difficult to sustain family farms and ranches, already a regional and national concern. The social and cultural aspects of the rural lifestyle would be fundamentally changed. Irrigated agriculture including, for example, Idaho's potatoes, would become more expensive as competition for (and prices of) water increased. As farming became more restricted and haying more costly, private lands would likely revert to a more natural appearance and character.
Agriculture is also a contributor to negative environmental impacts (e.g., nutrient and pesticide runoff, and erosion). If livestock production continues to be important, projected increases in heavy precipitation could cause high levels of run-off and nutrient leaching. Higher run-off levels into freshwater supplies would be likely to affect water quality in the region and could increase the potential for waterborne diseases. On the other hand, changes in cultivation practices such as low-till/no-till would be likely to increase the organic content of the soil and thereby increase its ability to sequester carbon, hold water, resist drought, avoid erosion, and limit nutrient loss. Increasing the organic content of the soil would also reduce the need for additional fertilizers -- a win-win situation for farmers, other water users, and the environment.
These tables illustrate the value of agriculture in the RMGB region.
Increased production associated with increased precipitation, warmer growing seasons, and CO2 fertilization would enhance these values, although additional costs such as changing crop varieties, changing cultivation and agricultural practices, and increased need for fertilizers, pesticides, and herbicides would reduce the gains to some degree. In addition, the effects of increased precipitation and longer growing seasons can be expected to improve grazing conditions for livestock, thus increasing income from ranching. But the public agencies that administer livestock grazing by private ranchers on public lands are under increasing pressure from environmental and outdoor-recreation groups to reduce the amount of livestock grazing allowed. It is therefore not clear that climate-change improvement in grazing conditions will be translated into increased livestock production and additional contribution to the region's economy.
Several options could be pursued to avoid or reduce potential negative impacts of climate change on RMGB agriculture. Strategies could be pursued that would:
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